9/7/2021 - By Dr. Jeff Atkinson

Conclusion:

Applications of POLYON® Controlled-Release Fertilizer in fall 2019 and spring 2020 in combination with Dimension® applied in spring 2020 provided 100% crabgrass control throughout 2020 (Figure 1; Figure 2).  POLYON® applied only in fall 2019 in combination with Dimension® applied in spring 2020 provided 94% crabgrass control. Dimension® applied in spring 2020 without fertility provided 91% control - significantly less crabgrass control than all POLYON® + Dimension® treatments. Fall + spring POLYON® without Dimension® provided up to 40% crabgrass control in early August, but control was poor (<5%) from late August onward (data not shown). 

Plots receiving fall 2019 POLYON® application resulted in higher turfgrass quality in spring 2020.  Application of POLYON® in fall 2019 and spring 2020 in combination with Dimension® applied in spring 2020 provided the highest turfgrass quality throughout the experiment. Fall 2019 POLYON® + spring 2020 Dimension® resulted in poorer turfgrass quality than fall POLYON® + spring POLYON® + spring Dimension® from June 20 until the conclusion of the experiment but greater quality than the Dimension® + no fertilizer program on most rating dates. Turfgrass quality in the spring 2020 Dimension® + no fertilizer treatment was low (= 6) from 6 June until the conclusion of the experiment despite >90% crabgrass control.

This trial further confirms the benefit of incorporating POLYON® Controlled-Release Fertilizer into a balanced approach program for smooth crabgrass control and enhanced turfgrass quality in fine turf areas.

Figure 1. Treatment effects from different fertility and herbicide programs for crabgrass control. F = Fall 2019; S = Spring 2020. Pictures taken August 31st, 2020. North Brunswick, NJ.

Figure 2. September 7th, 2020 – Smooth crabgrass (Digitaria ischaemum) control provided by fertilizer and herbicide treatments applied at the Rutgers Horticulture Farm No. 2 in North Brunswick, NJ. Fall 2019 - September 2020. Bars with different letters are statistically different at the a=0.05 level. 

Figure 3. Turfgrass quality following fertilizer and herbicide treatments applied to Kentucky Bluegrass (Poa pratensis) at the Rutgers Horticulture Farm No. 2 in North Brunswick, NJ. Turf quality was rated on a 1 to 9 scale with 1 representing poor turf quality and 9 representing excellent turf quality. Data points within the same rating date with different letters are statistically different at the a=0.05 level.